Changed definition of method call

  * Rewrote Wintermute::TemporaryPlugin::tryLoad() to pass the new plug-in
    upon creation, if successful.
Updated Winterute::Factory data.

  * Updated constant names.
  * Updated method calls.
Moved private data for Wintermute::Plugin.

  * Removed private definition of PluginPrivate.
  * Defined Wintermute::PluginPrivate into private header.